The most common and most likely answer to this crossword clue is the 2 letter word IN
I've seen this crossword clue in The Times
I
N
More clues leading to the result IN
- Such entertainment: motoring
- Relative's trendy wife bagging French article
- Paint Raymond keeps something for pending tasks
- Popular Los Angeles women’s 6? No
- Home bird, ultimately reserved, and kind with it
- Enthusiastic about favourite secret of Italians
- Term for pain in uncapped passion is concerning in Pope’s language
- One hopeless astride horse without outside help
- Hinting, awfully trendy item
- Aggressive or nice, somehow bottling a fury that's silly, about nothing?
Buddy explains!

The straight part
We know that "without outside help" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case without outside help = in.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does IN mean?
IN noun- A position of power or influence, or a way to get it.
- (chiefly in the plural) One who, or that which, is in; especially, one who is in office.
- The state of a batter/batsman who is currently batting; see innings.
- A re-entrant angle; a nook or corner.
- To enclose.
- To take in; to harvest.
- Located indoors, especially at home or at one's office or place of work.
- Located inside something.
- (of the ball or other playing implement) Falling or remaining within the bounds of the playing area.
- Inserted or fitted into something.
- Having been collected or received.
- In fashion; popular.
- Incoming.
- (of the sails of a vessel) Furled or stowed.
- Of the tide, at or near its highest level.
- With privilege or possession; used to denote a holding, possession, or seisin.
- Currently batting.
- Having familiarity or involvement with somebody.
- Having a favourable position, such as a position of influence or expected gain, in relation to another person.
- At or towards the interior of a defined space, such as a building or room.
- Towards the speaker or other reference point.
- So as to be enclosed or surrounded by something.
- Still eligible to play, e.g. able to bat in cricket and baseball.
- After the beginning of something.
- (in combination, after a verb) Denotes a gathering of people assembled for the stated activity, sometimes, though not always, suggesting a protest.
- Used to indicate location, inclusion, or position within spatial, temporal or other limits.
- Into.
- Used to indicate limit, qualification, condition, or circumstance.
- Used to indicate means, medium, format, genre, or instrumentality.
- Abbreviation of inch; inches.